co = coroutine.create(function()
    for i = 1, 10 do
        print(i)
        if i == 3 then
            print(coroutine.status(co)) -- running
            print(coroutine.running()) -- thread:xxx
        end
        coroutine.yield()
    end
end)

coroutine.resume(co) -- 输出1
coroutine.resume(co) -- 输出2
coroutine.resume(co) -- 输出3

print(coroutine.status(co)) -- 输出suspended
print(coroutine.running()) -- 由于协程处于suspended，当下没有正在运行的线程，因此输出nil